The invention relates to flexible polymeric hose of the elastomeric rubber or plastic type, but more particularly, the invention relates to flexible hose with means that facilitate bending and retaining the hose in a desired contour. The invention also relates to a method for making such hose without the need for extensive process or equipment changes.
Radiator hose is used extensively in automobiles for ducting a cooling fluid between an engine block and radiator. Some radiator hoses are molded with several compound curves to avoid interference with engine compartment components, such as V-belts, alternators, air pumps, brackets, or the like.
While curved or preformed hose solves routing and manufacturing assembly problems for an original equipment manufacturer, it creates inventory problems for an aftermarket hose distributor who finds it economically unfeasible to attempt to stock the required number of curved hose pieces for fitting all applications. Corrugated hose has become a popular replacement for curved hose to the small hose distributor because he can carry a small corrugated hose inventory that is suitable as a substitute for a variety of differently configured curved hoses. For example, one length of corrugated hose may be an effective substitute replacement for ten or more different curved hose configurations.
Corrugated hose has two sleeve or "cuff" ends that are interconnected by an intermediate corrugated sidewall that permits folding and inhibits kinking. An example of an early corrugated hose design appears in U.S. Pat. No. 314,440 to Eames. The Eames type hose is made on a mandrel and the corrugations are formed by helically wrapping a cord or rope around the hose to act as a mold for the corrugations.
Another type of hose is made by "pressure molding", which is achieved by internally pressurizing a hose and radially expanding it against a mold cavity of a desired configuration. An example of a corrugated hose made in such a manner is disclosed in U.S. Pat. No. 3,194,705 to Caplan. The Caplan hose also discloses an embodiment where a helical coil is embedded in the hose sidewall at either the corrugation's crests or valleys as a collapse resistance means when the hose is bent. Another type of hose that is radially expanded by pressure against the walls of a mold appears in U.S. Pat. No. 3,859,408 to Voss et al. Under the Voss et al method, a collapse resistance means may be inserted in the bore of the hose.
Although corrugated hose is an acceptable substitute for many curved hose applications, it has not been a "cure all" substitute for all curved hosed applications. Corrugated hose tends to take a symmetrical curved hose shape as its ends are positioned in parallel and/or angular misalignment from each other. For example, a hose may be shaped to a "S" bend, but both loops of the "S" tend to have the same bend radius. Many curved hose applications require unsymmetrical "S" bends to avoid interference with engine components. Various hose inserts have been developed for corrugated hose to solve the "S" bend problem. Examples of such corrugated hose with shape retentive inserts disposed in the hose bore appear in U.S. Pat. No. 4,327,775 to Tally and U.S. Pat. No. 4,456,034 to Bixby. While such hoses with internal inserts solve the hose "S" bend problem, they may introduce other problems in some hose applications. One problem is that the internal insert by design, defines an obstruction in the hose bore. Another problem is that the internal insert, being not fixably attached to the hose bore, may move during use and thereby permit an especially long hose to slump into an undesirable shape.
There are some hoses with reformable inserts in their sidewalls which avoid the obstruction problem as well as the slumping problem; however, such hoses have relatively small diameters and are made by extrusion processes that are not applicable to a corrugated sidewall construction or a pressure molding process. An example of a small diameter hose for use as automotive heater hose, which has a longitudinally oriented reinforcement in its sidewall appears in U.S. Pat. No. 4,463,779 to Wink et al. A hose with several longitudinally oriented elements disposed in its sidewall appears in U.S. Pat. No. 2,998,028 to Rohde. The Rohde construction cannot be used to make hose formed by the pressure molding process such as taught by Caplan or a cording process such as taught by Eames because under each of these process, pressure is applied to the hose sidewall during the curing. Pressure on the sidewall would collapse and seal the longitudinal wire receiving cavity during curing. The Wink et al hose construction is also inapplicable for making a hose with a corrugated sidewall. A longitudinal cavity formed in the hose sidewall would be collapsed and sealed as the sidewall is pressurized to take a corrugated shape. A wire coextruded with the Wink et al hose would prevent or substantially inhibit a sidewall to be formed into a corrugated shape under either the Caplan or Eames methods of forming a hose sidewall.